In GC/MS analysis, various components contained in a test sample are passed through a column and separated over time, and the ions generated from each of the separated components are separated according to their mass-charge ratios (m/z) by a mass spectrograph such as a quadrupole mass filter and detected with a detector. When identifying unknown compounds contained in a sample, scan measurements of prescribed mass ranges (m/z ranges) are ordinarily executed repeatedly in MS, and a mass spectrum is created for each of the scan measurements. A graph in which the intensity determined by adding all of the ion intensities in each mass spectrum is plotted over time is a total ion current chromatogram (TIC), and a graph in which attention is focused on ions having certain mass-charge ratios and the intensities of these ions are plotted over time is an extracted ion chromatogram (EIC).
When assaying a compound contained in a sample by GC/MS analysis or LC/MS analysis, the ions characterizing the compound are typically determined to be quantitative ions (also called target ions), and quantitative values—that is, the component content or concentration—are calculated from the chromatogram peaks appearing in the vicinity of the retention time of the target compound in an EIC of the quantitative ions obtained by means of actual measurements. Ions corresponding to a peak for which the signal intensity is highest in a typical mass spectrum of the compound are ordinarily selected as quantitative ions.
Although the quantitative ions described above are ions which characterize each compound, various contaminants may be included in an actual sample, and components may overlap due to insufficient component separation in the previous stage of GC or LC as a result of inappropriate analytical conditions. In such cases, it is sometimes difficult to confirm from chromatogram peaks of quantitative ions alone whether the peaks indeed originate from the target compound. In such cases, ions having a different mass-charge ratio characterizing the compound are selected as confirmation ions separately from the quantitative ions, and it is confirmed—that is, identified—that the chromatogram peaks of the quantitative ions originate from the target compound using the relative ratio (hereafter called the “confirmation ion ratio”) of the signal intensity of the confirmation ion peaks and the signal intensity of the quantitative ion peaks in the mass spectrum. In addition, confirmation ions of one type are often insufficient to accurately confirm the quantitative ion peaks of a compound, and it is common for a plurality of types of confirmation ions to be used for a single compound (see Patent Document 1).
In a conventional device, a confirmation ion ratio found from data obtained by performing mass spectrometry on a standard sample of a target compound is stored in advance in a storage part as an ideal ratio, and an analyst is able to determine whether the confirmation ion ratio of an identified compound is appropriate by comparing the numerical value of the confirmation ion ratio found from data obtained by analyzing the actual sample and the ideal ratio described above. However, such a determination by numerical values is not very efficient and is prone to misjudgment. Moreover, in order for the analyst to determine whether the identification of a compound is appropriate, it is also necessary to visually confirm the shapes and heights of peaks in the EIC, but it is difficult for the analyst to determine whether a peak height is appropriate based on the confirmation ion ratio by simply examining the EIC.
In particular, in the case of multi-component analysis, it is necessary for the analyst to visually confirm whether peaks in the EIC are appropriate based on the confirmation ion ratio one by one for an enormous number of compounds ranging from several tens to several hundreds of compounds. Therefore, in order to increase the throughput of such an operation, the analyst is required to assess the appropriateness of each compound in a short amount of time, but such an assessment is difficult to make in a short amount of time with the conventional method described above, and there is also a high probability of causing misjudgment and oversight.
Patent Document 1—Japanese Unexamined Patent Application Publication 2006-189279